TRAVERSE CITY, Mich. -- A U.S.-Canadian pact to clean up the Great Lakes has run its course after more than three decades and should be scrapped in favor of a more effective, modern strategy, a binational panel said Tuesday.

The Great Lakes Water Quality Agreement of 1972 has inspired progress on some of the ecosystem's biggest threats, such as untreated sewage and industrial toxic discharges, said a report by the International Joint Commission, which advises both countries about the lakes.

Yet the agreement's success stories are offset by lingering problems such as unfinished cleanup of highly contaminated harbors and rivers, the report said.

The agreement, which hasn't been updated since 1987, is cumbersome and lacks tools for prodding government to take action, the report said. And it overlooks emerging issues such as invasive species, habitat loss, climate change and urban sprawl.

"Threats to water quality persist, new ones have emerged and scientific advances have yielded new understandings of problems that, in turn, point to different solutions," the report said. "What was once judged farsighted and robust enough to protect vulnerable populations of humans, fish and wildlife is no longer sufficient."

Instead of updating the agreement yet again, the commission called for a new plan. It should identify ambitious goals, set timelines and yardsticks for progress, hold governments accountable and adapt quickly to changing circumstances, the report said.

"If you look at the agreement now, there are lots of objectives and they're worthwhile, but they're not linked with deadlines," said Herb Gray, the Canadian co-chairman of the commission. "We're just saying there's more that has to be done, and it has to be done in an up-to-date manner."

The new agreement should take a more holistic approach to Great Lakes protection by focusing on the biological integrity of entire watersheds and ecosystems and making human health a top priority, the report said.

The original water quality agreement was signed by President Nixon and Canadian Prime Minister Pierre Trudeau. It established a framework for international cooperation on restoring the health of the Great Lakes, which make up about 20 percent of the world's surface fresh water.

At that time, large sections of the lakes _ especially Erie and Ontario _ were suffering from chemical pollution. The oil-caked surface of the Cuyahoga River, which flows into Lake Erie near Cleveland, had caught fire. Phosphorus buildup fueled runaway algae blooms that sucked oxygen from the water, causing massive fish kills.

The most recent version of the agreement identified another high-priority issue: cleaning up 43 toxic "hot spots" _ badly polluted harbors and rivers. Nearly 20 years later, the job hasn't been finished for most of them.

A committee with representatives of both countries began meeting in April to lay the groundwork for another update.

But the International Joint Commission, which produces biennial progress reports on the agreement, said simply fine-tuning the status quo was no longer enough. The commission reached its conclusion after holding a series of public meetings across the Great Lakes region over the past year.

Reg Gilbert, senior coordinator with the environmentalist group Great Lakes United, said the water quality agreement had lost steam over the past two decades.

"People started thinking the Great Lakes weren't in trouble any more," he said. "And the political climate has changed in the U.S., and even in Canada. There's less faith that government can make a difference."

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EDITOR'S NOTE _ John Flesher is the AP correspondent in Traverse City and has covered environmental issues since 1992.